Azteca andreae
Encyclopedia
Azteca andreae is an arboreal
ant
species found in the tropics
of South America
, most notably in French Guiana
. They are most notable for their predatory
skills and strength. They are ambush predator
s that are able to capture and eat other insects much greater than their own size.
is slightly more than 5mm in length.
, of select plant species. When the queens start a new colony
, they apparently limit their colonies to Cecropia
trees. They will inhabit multiple different species of tree, but they have a preference for Cecropia obtusa. Up to 8350 workers live in each tree. The queens initially start the colonies inside of the tree
, but the ants will eventually build external carton nest
s.
that the plant provides. In return, the plant receives security from herbivores that may eat the plant, because the ants hunt on the plant and eat many of the plant’s predators. This symbiosis
benefits both the plant and ants.
. There, they are invisible from above except for their mandibles, which hang outside the edge waiting for prey. Many times, the ants will occupy each leaf of the plant.
When an insect lands on the leaf, three to ten of the closest ants immediately attack and drive the prey to the leaf margin, where more ambushing ants will congregate and attack. Large prey was only captured if on the edge of the leaf, because the ants use their specialized leg
s to hold onto the velvety surface underneath ‘’C. obtusa’’ leaves. This mechanism essentially acts like Velcro
©, with the many small hooks on the legs of the ant gripping onto the velvet of the underside of the leaf. Because only the bottom of the leaf has this surface, the ants can only really capture prey when they are holding onto the leaf from the underside. This is the main factor that allows the ants to capture such massive prey. After catching their prey, they will either start tearing it to shreds on the spot or take it back to the colony and cut it up into smaller pieces.
In an experiment by Alain Dejean et al. (2010), the ants captured more prey when hunting on C. obtusa than any other plant. The proposed explanation for this was the enhanced gripping power resulting from the Velcro©-like mechanism that was absent on all the other plants. In addition, the research team tested the limits of the ants’ strength. They placed a weight on a thread, which they introduced to an ant that immediately grabbed on to the thread with its mandibles. An individual ant held onto weights up to eight grams, or 5.714 times the ant’s weight. Collectively, they were observed to capture a locust that weighed 18.61 grams, or 13,350 times the average weight of a single worker. This is one of the largest feats of strength documented in the entire animal world.
Arboreal locomotion
Arboreal locomotion is the locomotion of animals in trees. In every habitat in which trees are present, animals have evolved to move in them. Some animals may only scale trees occasionally, while others are exclusively arboreal. These habitats pose numerous mechanical challenges to animals...
ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
species found in the tropics
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately N and the Tropic of Capricorn in the southern hemisphere at S; these latitudes correspond to the axial tilt of the Earth...
of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, most notably in French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
. They are most notable for their predatory
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
skills and strength. They are ambush predator
Ambush predator
Ambush predators or sit-and-wait predators are carnivorous animals that capture prey by stealth or cunning, not by speed or necessarily by strength. These organisms usually hide motionless and wait for prey to come within striking distance. They are often camouflaged, and may be solitary...
s that are able to capture and eat other insects much greater than their own size.
Physical Characteristics
A. andreae have dark brown, shiny bodies covered in white hair. The workers are a little less than 3mm in length, and the queenQueen ant
A queen ant is an adult, reproducing female ant in an ant colony; generally she will be the mother of all the other ants in that colony. Some female ants do not need to mate to produce offspring, reproducing through asexual parthenogenesis or cloning and all of those offspring will be female.Ant...
is slightly more than 5mm in length.
Habitat
The ants live in the hollow internodes, or the spaces in between nodes on the plant stemPlant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
, of select plant species. When the queens start a new colony
Colony (biology)
In biology, a colony reference to several individual organisms of the same species living closely together, usually for mutual benefit, such as stronger defense or the ability to attack bigger prey. Some insects live only in colonies...
, they apparently limit their colonies to Cecropia
Cecropia
Cecropia is a Neotropical genus presently consisting of sixty-one recognized species with a highly distinctive lineage of dioecious trees....
trees. They will inhabit multiple different species of tree, but they have a preference for Cecropia obtusa. Up to 8350 workers live in each tree. The queens initially start the colonies inside of the tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
, but the ants will eventually build external carton nest
Nest
A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
s.
Plant-Ant Symbiosis
Often, the ants will not only receive housing from the plant; they will eat extrafloral nectar and food bodiesBeltian body
A Beltian body is a structure found on the leaves of some species of Acacia. Beltian bodies, named after Thomas Belt, are found on the tips of each leaflet and are rich in lipids and proteins and often red in colour. They are believed to have evolved in a symbiotic relationship with ants...
that the plant provides. In return, the plant receives security from herbivores that may eat the plant, because the ants hunt on the plant and eat many of the plant’s predators. This symbiosis
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
benefits both the plant and ants.
Predatory Behavior
A. andreae use ambush predation to hunt insects many times their own size. The ants will actually position themselves side-by-side next to each other underneath the edge a leafLeaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
. There, they are invisible from above except for their mandibles, which hang outside the edge waiting for prey. Many times, the ants will occupy each leaf of the plant.
When an insect lands on the leaf, three to ten of the closest ants immediately attack and drive the prey to the leaf margin, where more ambushing ants will congregate and attack. Large prey was only captured if on the edge of the leaf, because the ants use their specialized leg
Arthropod leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...
s to hold onto the velvety surface underneath ‘’C. obtusa’’ leaves. This mechanism essentially acts like Velcro
Velcro
Velcro is the brand name of the first commercially marketed fabric hook-and-loop fastener, invented in 1948 by the Swiss electrical engineer George de Mestral...
©, with the many small hooks on the legs of the ant gripping onto the velvet of the underside of the leaf. Because only the bottom of the leaf has this surface, the ants can only really capture prey when they are holding onto the leaf from the underside. This is the main factor that allows the ants to capture such massive prey. After catching their prey, they will either start tearing it to shreds on the spot or take it back to the colony and cut it up into smaller pieces.
In an experiment by Alain Dejean et al. (2010), the ants captured more prey when hunting on C. obtusa than any other plant. The proposed explanation for this was the enhanced gripping power resulting from the Velcro©-like mechanism that was absent on all the other plants. In addition, the research team tested the limits of the ants’ strength. They placed a weight on a thread, which they introduced to an ant that immediately grabbed on to the thread with its mandibles. An individual ant held onto weights up to eight grams, or 5.714 times the ant’s weight. Collectively, they were observed to capture a locust that weighed 18.61 grams, or 13,350 times the average weight of a single worker. This is one of the largest feats of strength documented in the entire animal world.